When I hit the brakes, my left brake light does not work. When I turn on the lights at night, the taillight works, but, no brake light. The turn signal and backup lights work. Aftermarket LED taillights if that helps at all... Is it a relay, or a bad wire??? Fuse isnt blown. HELP!!!

 

Replace your light bulb. One of the "Tungsten Filament" inside that bulb is gone. For brake light bulb, there are 2s. Signal bulb only has 1.

 

there are about 20-30 individual LED lights..... Is it a ground??